The enzyme responsible for O2 ion production by stimulated neutrophils will be purified and characterized. An antibody will be raised against the purified enzyme, and with this antibody cross-reacting material will be sought in resting phagocytes, phagocytes from patients with chronic granulomatous disease and other familial abnormalities of phagocyte function, and non-phagocytic cells. This biochemical basis for the activation of the O2 ion-forming enzyme will be investigated by a variety of methods. Attempts will be made to develop a model for chronic granulomatous disease based on the exhaustion of the O2 ion-forming enzyme by F ion. The role of myeloperoxidase-dependent and -independent oxidative microbicidal mechanisms will be studied with the neutrophils themselves and with artificial O2 ion-generating systems using various species of bacteria and various mutant strains within a single species.